SRP--Where the RNA and Membrane Worlds Meet

Working out how the signal recognition particle (SRP) of cells directs newly synthesized proteins destined for secretion to the endoplasmic reticulum (ER) has proved a gargantuan task. That task has just been made easier, as explained in a Perspective by Peter Walter and colleagues, by the solving of the crystal structure of the RNA-protein core of the SRP ( Batey et al .)